+1(514) 937-9445 or Toll-free (Canada & US) +1 (888) 947-9445
Looks like it was about 50% in 2014-2015, but has dropped in recent years. Just to add, there are loads of outstanding claims from 2014 on (more than half). You could read that a bunch of ways, so take it with a grain of salt. Also note the appeal rate for all year for rejected claims is about 10-15% acceptance for all countries. It seems once your claim is denied, you are almost putting off the inevitable removal.
 
IRB statistics showed from Jan to Jun 2018 acceptance rate is 50%.